I've read the short story, "The Lottery" before. I think people were probably bitter because of the ending, and a lot of people probably weren't able to understand the story, the theme, and why she died. They might have also thought it was just a little to dark/sad.
Or because one of the themes of the book was just because something is tradition doesn't mean you should follow it. So people could've thought that it was questioning religion, tradition, society or even the government.